Attribute handling cleanup.

Changes:
* early detection are attributes handled at all (to save cycles doing things thrown away later)
* cleanup of DefaultAttributesHandler by means of making fields private and final. removal of unused methods
* deprecated ancient StorageFileItemInspector that were operating on java.io.File (and potentially performed catastrophic)
* update core inspectors, made them StorageItemInspector's, reduced size by reusing code from core
* fixed attribute expansion, streamlined logic (detection of unneeded work happens way earlier than before)
* affected UTs updated
No code change, just javadoc.
Merge pull request #182 from sonatype/attribute-handling-cleanup

Attribute handling cleanup.